linux-kernel - RE: [PATCH 2/2] ufs: don't use the fair tag sharings

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Date:   Tue, 9 May 2023 08:03:01 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     Ed Tsai <ed.tsai@...iatek.com>, "axboe@...nel.dk" <axboe@...nel.dk>
CC:     "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "bvanassche@....org" <bvanassche@....org>,
        "stanley.chu@...iatek.com" <stanley.chu@...iatek.com>,
        "peter.wang@...iatek.com" <peter.wang@...iatek.com>,
        "chun-hung.wu@...iatek.com" <chun-hung.wu@...iatek.com>,
        "alice.chao@...iatek.com" <alice.chao@...iatek.com>,
        "powen.kao@...iatek.com" <powen.kao@...iatek.com>,
        "naomi.chu@...iatek.com" <naomi.chu@...iatek.com>,
        "wsd_upstream@...iatek.com" <wsd_upstream@...iatek.com>
Subject: RE: [PATCH 2/2] ufs: don't use the fair tag sharings

 
> The tags allocation is limited by the fair sharing algorithm. It hurts
> the performance for UFS devices, because the queue depth of general I/O
> is reduced by half once the UFS send a control command.
Ack.

However, I think the decision of that should be of the platform owner,
And not in the core driver.

Thanks,
Avri

> 
> Signed-off-by: Ed Tsai <ed.tsai@...iatek.com>
> ---
>  drivers/ufs/core/ufshcd.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 17d7bb875fee..e96a50265285 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -5149,6 +5149,9 @@ static int ufshcd_slave_configure(struct scsi_device
> *sdev)
>         blk_queue_update_dma_pad(q, PRDT_DATA_BYTE_COUNT_PAD - 1);
>         if (hba->quirks & UFSHCD_QUIRK_4KB_DMA_ALIGNMENT)
>                 blk_queue_update_dma_alignment(q, 4096 - 1);
> +
> +       blk_queue_flag_clear(QUEUE_FLAG_FAIR_TAG_SHARING, q);
> +
>         /*
>          * Block runtime-pm until all consumers are added.
>          * Refer ufshcd_setup_links().
> --
> 2.18.0